Work

Effect of acidification on the chronic toxicity of diclofenac to Daphnia magna

Year: 2025

Type: article

Abstract: Pharmaceuticals, as ionizable compounds, are a challenging group of pollutants to analyze because the pH of the environment can alter its ecotoxicological features. However, changes in the toxicity of pharmaceuticals toward aquatic organisms were observed even when there was no change in the ionization of the molecules with a pH shift. Therefore, we conducted a study that aimed to check how pH influences the chronic toxicity of diclofenac (DCF, pKa ≈ 4.0) toward Daphnia magna at two pH levels, 7.0 and 8.7, where DCF is obtained as relatively polar anion. The performance of the experiment with OECD 211 was found to be challenging because of the medium pH shift during the exposure test. Acidification increased the toxicity of DCF, reducing the number of neonates (at a concentration of 1.3 mg L -1 ) and showing a tendency towards delayed hatching and reduced hatchling numbers. In addition, the acidification itself also changes D. magna reproduction, affecting the number of hatchlings and the first day of hatching. We conclude that the pH, as a factor of toxicity modulation for ionizable compounds, needs to be evaluated and presented in scientific protocols.

Source: Aquatic Toxicology

DOI: 10.1016/j.aquatox.2025.107497

Authors: Katarzyna Bethke, Magda Caban

Institution: University of Gdańsk

Language: English

Topic: Pharmaceutical and Antibiotic Environmental Impacts

Subfield: Pollution

Field: Environmental Science

Domain: Physical Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,320